Hi,

So I recently replaced the intake upper gaskets and front side valve cover gaskets as well as spark plugs (still has to replace the other valve cover gasket due to oil leaking in spark plugs near the firewall).

Now all codes from before are gone. The only code left is P0420 and a bad smoke exhaust smell inside the cabin when driving. From reading a lot I'm suspecting an exhaust leak that is causing the P0420 as well (unless the cat is gone bad). Today I'm trying the lucas + CRC Guaranteed To Pass additives together to see if they will help clear the P0420 as some people have said .. jsut to get it passed inspections.

I need help on how to diagnose the smoke smell inside the cabinet and where do I start to diagnose the exhaust leak (if any)? I'm planning to take the intake manifold off and replace the lower gaskets as well as the back valve cover gaskets this weekend.

Thanks in advance.

 

well you can start by looking where the header meets the cats. The bolts could have rusted or are loose. Next try the down y pipe that heads to the flex pipe. My guess is the header/cat next to the firewall may be the issue. It was where my leak was. I put new bolts on and a new steel ring gasket with some hi heat gasket maker. issue solved. Let us know


Good luck,
The Dr!

 

Dr. Dome. Thanks for putting me on the right track. This maybe silly but for the first step do I look at that from the top of the engine or from under the car? what is easier? and also how easy is it to put the steel ring gasket (is that the same as the exhaust manifold gasket?).

Thanks again.

 

abdo, I would say to make sure the motor is cold and then get the front end up in the air. From there, ensure the car is in park (and remains there) and start up the motor. From there, I would do a quick run under the car to see if you can see where the smoke will be coming from. Then as the motor warms up, you can open the hood and do some more looking. Hopefully this will show you where the leak is coming from. There are enough joints that I would hate to start guessing as to where it can be coming from. With running the heat, any leak in the engine bay is going to get sucked up into the intake of the dash heater and blow that smoke into your face.

You may also find taking a small piece of tubing (say 1/4" ID tygon tubing) and running it around all the joints as you hold the other end near your ear, you will hear a hissing/air rushing sound as you get near the leak.

Another silly question, have you recently had your motor oil or transfer case fluid changed? If so, that may be the source of your smell too. something to ponder.

 

Thermo,

Thanks for your response. I appreciate it. I recently replaced the upstream o2 sensor next to the radiator , spark plugs, front valve cover gasket and took off then put back and tightened the imt o rings (vendor sent wrong ones so I had to put the old ones back).

I'm also now getting P0420 AND P0430 as the only codes left. I'm seriously thinking about the O2 downstream sensor defouler idea to help pass the emissions until I figure out if I really need to replace the cats ... now that I think about it I suspect a leak from around the O2 sensor as that is the only place I messed with near the exhaust .. does that make sense?

 

And the motor oil was changed but some good time ago (less than 3000 miles but quite some time ago)... Planning to change it again soon.

 

Abdo, since you mentioned that you replaced the one O2 sensor, I would bet that the leak you have is going to be right in that area. You didn't mention any exhaust work before. Normally when you have a problem like this, you always start at where you just did work. It may be that in the process of trying to get the O2 sensor out, you flexed the exhaust just a little bit to cause a leak.